EURASIAN MINING • 1 2015 Technology and technics of ore preparation processes 7 feed for the rod mill i e 10000 μm in accordance with Table The value of P 80 is accepted based on the required grain-size characteristics of the ball mill discharge The oversize crusher feed size distribution oscf and the primary cyclone feed size distribution pcfd are estimated utilising the SAG mill grate size and discharge screen aperture sizes and the Rosin-Rammler size distribution function which has been selected for its convenience and since it "has been found to fit many

Autogenous and Semi

According to MacPherson and Turner the optimum feed size consistent with maximum power draw is given by the relation (9 1) F 80 = 53 5 D 0 67 where F 80 = feed 80% passing size in millimetre D = inside diameter of the mill in metres The feed in AG and SAG mills contains a fraction that serves as the grinding medium These larger ore

The Sag mill uses lifting plates along the interior of the drum which lift material throughout the rotations causing them to fall onto one another to promote crushing A ball mill has many steel or porcelain balls put in a drum to grind the feed between balls and between the balls and drum inner wall as the drum rotates This mill is capable

SAG and ball mills grind material through different actions and are usually applied in different stages of the process SAG mills usually have a larger diameter than length and are used to reduce large feed size ore (typically ~300mm) down to ~3mm often for further grinding in a secondary process

Morrell Mi (SMC) SAG ball mill Model This is a SAG or AG mill plus ball mill model that estimates the specific energy consumption (E SAG) using the equations of Morrell (2004) Testwork Required The SMC™ test stored in the DWT testwork table (SMC is a Drop Weight Test) Bond ball mill work index

Amstar SAG/AG Mills range in size from 4 3m through 12 2m in diameter with powers as high as 28 000 kW Our team of product engineers continually improves SAG/AG Mill designs in order to provide the most robust safe and efficient grinding mills available

AMIT 135: Lesson 5 Crushing

This means that the number of crushing stages can be reduced depending on the feed size accepted by primary grinding stage Image of a "Classical" 3-stage ore crushing prior to rod mill [image: (135-5-1)] Diagram of Typical 1-2 stage ore crushing prior to AG-SAG mill [image: (135-5-2)] Calculation of Reduction Ratio in Crushing

8-3 Centrifugal force outward Fc mp 2 Dm 2 (8 1) is the angular velocity mp is the mass of any particle (media or charge) in the mill and Dm is the diameter of the mill inside the liners Gravitational force Fg mpg (8 2) The particle will remain

Raw Bond Model This is a SAG or AG mill plus ball mill model that estimates the specific energy consumption (E SAG) using the 1979 Barratt equation and the classical Bond work index equation including Rowland efficiency factors The model allows a manual calibration factor on both equations (CF SAG and CF ball respectively) This formula usually gives higher total circuit

Two new SAG milling models are developed in this work able to predict power or specific energy consumption including the usual design variables such as mill size balls charge level solids concentration in the SAG mill feed and % of critical speed but adding a variable that represents the feed size distribution The −6″ +1″ (−152

SAG MILL DISCHARGE SCREENS-TROMMEL vs VIBRATING Tony Moon RTZ What I'd like to talk about is probably one of the nastiest bits of mill design for a grinding circuit and that is the choice of what do you use on a SAG mill discharge? Do you use vibrating screens or trommel screens? What many of you probably don't realize is that at

the primary mill product in an attempt to control and possibly reduce flotation feed size variability The objectives of this study were to: 1 Evaluate the suitability and reliability of the in-line instrument used to measure real-time data 2 Determine the minimum sampling frequency necessary to capture sufficient circuit dynamics for real-time

Single stage SAG Mills are very beneficial in reducing CAPEX for plants with a staged throughput approach When future tonnage is to be increased the SAG Mill can feed downstream ball milling to boost capacity Fuller-Traylor SAG/AG Mills range in size from 4 3m through 12 2m in diameter with powers as high as 28 000 kW Our team of product

achieve a certain transfer size based on the 80 per cent passing value an ineffi ciency factor must be applied to the SE of single stage ball mills rod mills or AG/SAG mills when calculating power according to the Bond Third Theory method Rod mill and AG/SAG mill products are similar and tend to

Optimization of mill performance by using

Optimization of mill performance by using online ball and pulp measurements Soon after a stop a mill is a dangerous place to enter for the personnel tasked with taking measurements or samples Crash stops are difficult to handle The mill and all feed streams should be stopped simultaneously but often they are stopped around about the same

2 A SAG mill operates with a 10 000 hp motor Typical power draw is 80% of maximum The 80 percent passing feed size to the mill is 6 inches and the mill discharge has an 80 percent passing size of 2 3 mm Calculate the Operating Work Index for this mill if the feed tonnage rate is 1175 tonnes per hour

SAG mill discharge control is quite involved due to few interactive variables such as mill discharge sump level classification hydro-cyclone variables (feed density flow and pressure) and water feed rate to the sump Model predictive control (MPC) which is a multi-input multi-output (MIMO) controller is very suitable for this purpose If a particle size analyser is installed it can

Feed size effects what size is important? historically Mine-to-Mill has – focussed on blasting alone – generation of more fines • pass through SAG mill onto ball mill circuits • higher throughput (e g 10% to 30%) • coarser grind size (possibly) fine 25mm medium 25 -

Every mining operation has a unique grinding process has experience of over 8 000 grinding mills globally including manufacturing and delivering the largest SAG/AG mills in the world Our experts welcome the opportunity to assist you with circuit and circuit control design as well as start-up operation and optimization of your mill

AG/SAG mills accomplish the same size reduction work as 2 or 3 stages of crushing and screening Features The feed size for these mills is limited to the maximum size that can be practically conveyed and introduced into the large mill feed chutes

Media to media contact for rods mills is linear rather than point to point (as with balls) and are much heavier The larger feed tends to separate rods at the feed end such that larger particles are preferentially abraded This leads to a narrower size distribution and significantly less slime compared to ball mills

P 80 is the mill circuit product size in micrometers F 80 is the mill circuit feed size in micrometers Rod mill A rotating drum causes friction and attrition between steel rods and ore particles [citation needed] But note that the term 'rod mill' is also used as a synonym for a slitting mill which makes rods of iron or other metal Rod

Although it is well known and easily experienced that the feed size distribution influences the throughput and stability of operation of a semi-autogenous grinding (SAG) mill the details are poorly understood since it is often only the input and output measurements that are used to identify unfavourable in-mill conditions

SAG mill throughput is often a bottleneck to increasing plant productivity Improved size distribution control in the mill feed can be used to increase mill production This can be accomplished by controlling blast fragmentation as a function of energy input and rock characteristics Such an approach requires the integration of rock fragmentation and